1. Field of the Invention
The present invention relates to integrated circuit technology and imaging array technology and amplifier technology for use in integrated circuit applications. More particularly, the present invention relates to a high density imaging array integrated circuit including a sense amplifier for use in such an array.
2. The Prior Art
Sense amplifier circuits in general are known in the prior art. Sense amplifier circuits for use in imaging arrays are also known in the prior art.
A high-density photosensing imager may be realized by an array of bipolar transistors with bases capacitively coupled to sense lines, as previously disclosed by Mead et al. in U.S. Pat. Nos. 5,097,305, 5,260,592, and 5,324,958. In such an imager it is necessary to construct a sense amplifier that has a gain of 1000 or greater. It would be advantageous for such a sense amplifier to fit into a width of one pixel in the imager array (6 microns in a 1 micron process) so as to be able to provide a compact, efficient photosensing imager system. It is desirable that the sense amplifier have low noise, low power dissipation, and a compressive input-output characteristic such that it will decrease its gain gradually at large inputs rather than clip abruptly. Traditional amplifier designs either have too much noise or cannot be made to fit in the width available.
It is therefore an object of the present invention to provide a sense amplifier which overcomes one or more shortcomings of the prior art.
Yet another object of the present invention is to provide a sense amplifier which can fit into the width of a single pixel in a photosensor array.
It is a further object of the present invention to provide a sense amplifier having low noise, low power dissipation, and a compressive input-output characteristic such that it will decrease its gain gradually at large inputs rather than clip abruptly.
Yet a further object of the present invention is to provide an integrated photosensing imager system including a sense amplifier which can fit into the width of a single pixel in a photosensor array.
Another object of the present invention is to provide an integrated photosensing imager system including a sense amplifier having low noise, low power dissipation, and a compressive input-output characteristic such that it will decrease its gain gradually at large inputs rather than clip abruptly and which can fit into the width of a single pixel in a photosensor array.